Secondary battery

ABSTRACT

An electrode assembly for a secondary battery comprising an adiabatic plate attached to the negative electrode plate is disclosed. The electrode assembly comprises a positive electrode plate having a positive electrode collector, a positive electrode coating, and a non-coated area on the positive electrode collector. The negative electrode plate has a negative electrode collector, a negative electrode coating, and a non-coated area on the negative electrode collector. A separator insulates the positive and negative electrode plates. Positive and negative electrode tabs are attached to the non-coated areas of the positive and negative electrode collectors. The negative electrode plate has an adiabatic plate attached to the surface of a non-coated area of the negative electrode collector that is opposite the surface to which the negative electrode tab is attached. This construction improves battery stability and prevents short circuits caused either by heat generated during overcharging or by an internal short circuit.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication number 2004-0037501, filed May 25, 2004 in the KoreanIntellectual Property Office, the entire content of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to secondary batteries using lithium ions,and more particularly to secondary batteries having adiabatic platesattached to a surface of the negative electrode plate. The adiabaticplate is fixed to the surface opposite the surface to which the negativeelectrode tab is fixed. This construction prevents an additional shortcircuit between the negative electrode plate and the negative electrodetab when an internal short circuit occurs. This construction alsoprevents an additional short circuit when the separator melts due toheat generated from the electrode tab during overcharging orover-discharging of the battery.

BACKGROUND OF THE INVENTION

As is generally known in the art, secondary batteries are batteries thatcan be charged and discharged, unlike primary batteries which cannot becharged. Secondary batteries are widely used in cutting-edge electronicappliances, including cellular phones, laptop computers, and camcorders.

Lithium secondary batteries are examples of such secondary batteries andhave operation voltages of about 3.7 V. These operation voltages areabout three times greater than those of nickel-cadmium batteries ornickel-hydrogen batteries which are often used as power sources for manyportable electronic appliances. Lithium secondary batteries also havehigh energy density per unit weight. For these reasons, lithiumsecondary batteries have been widely used.

Lithium secondary batteries generally use lithium-based oxides as thepositive active materials, and use carbon materials as the negativeactive materials. Lithium secondary batteries are classified into liquidelectrolyte batteries and polymer electrolyte batteries depending on thetype of electrolyte used. Liquid electrolyte batteries are referred toas lithium ion batteries and polymer electrolyte batteries are referredto as lithium polymer batteries.

There are various types of lithium secondary batteries, includingcylinders, cans, and pouches. As shown in FIGS. 1 and 2, a typicalcan-type lithium ion secondary battery includes a can 10, an electrodeassembly 20 contained in the can 10, and a cap assembly 70 for sealingthe top opening of the can 10. The can 10 may comprise a metallic memberhaving the shape of a cuboid, and the can itself can be a terminal. Thecan 10 has an open top surface 10 a, and the electrode assembly 20 isplaced in the can 10 through the open top surface 10 a.

The electrode assembly 20 includes a positive electrode plate 30, anegative electrode plate 40, and a separator 50. The separator 50 ispositioned between the positive and negative electrode plates 30 and 40,respectively, and the entire assembly is then wound, creating a jellyroll construction.

The positive electrode plate 30 includes a positive electrode collector32 comprising thin aluminum foil and a positive electrode coating 34comprising a lithium-based oxide as the main component. The positiveelectrode coating 34 is coated on both surfaces of the positiveelectrode collector 32. The positive electrode collector 32 also hasnon-coated areas 32 a, which are not coated with the positive electrodecoating 34. The non-coated areas 32 a are located on both ends of thepositive electrode plate 30. A positive electrode tab 36 is fixed to oneof the non-coated areas 32 a by ultrasonic welding such that both endsof the positive electrode tab 36 protrude from the upper end of thepositive electrode collector 32. The positive electrode tab 36 usuallycomprises nickel or nickel alloy, but other metals may also be used.

The negative electrode plate 40 includes a negative electrode collector42 comprising thin copper foil and a negative electrode coating 44comprising a carbon material as the main component. The negativeelectrode coating 44 is coated on both surfaces of the negativeelectrode collector 42. The negative electrode collector 42 also hasnon-coated areas 42 a, which are not coated with the negative electrodecoating 44. The non-coated areas 42 a are located on both ends of thenegative electrode plate. A negative electrode tab 46 is fixed to one ofthe non-coated areas 42 a by ultrasonic welding such that both ends ofthe tab 46 protrude from the upper end of the negative electrodecollector 42. The negative electrode tab 46 usually comprises nickel ornickel alloy, but other metals may also be used.

The separator 50 is positioned between the positive and negativeelectrode plates 30 and 40, respectively, thereby insulating theelectrode plates from each other. The separator 50 comprisespolyethylene, polypropylene, or a composite film of polyethylene andpolypropylene. The separator 50 usually has a width larger than thewidths of the positive and negative electrode plates 30 and 40,respectively, to prevent a short circuit between the electrode plates.

The cap assembly 70 includes a cap plate 71, an insulation plate 72, aterminal plate 23, and a negative electrode terminal 74. The capassembly 70 is first coupled to a separate insulation case 79, and isthen coupled to the open top surface 10 a of the can 10, thereby sealingthe can.

Heat is generated in the can either when the battery is overcharged oroverdischarged, or when a short circuit occurs between the electrodes.In particular, the heat concentrates on the part of the can havingincreased internal resistance, i.e. where different metals are bondedtogether to weld the electrode plate to the electrode tab. As heatconcentrates around the electrode tab, the separator, which insulatesthe positive and negative electrode plates from each other, melts andcontracts. As a result, an additional short circuit occurs between theelectrode plates.

Secondary batteries tend to have larger capacity, thereby increasing theenergy density of such batteries. The heat generated at the electrodetabs of these batteries due to initial heating causes short circuitsbetween the electrode plates. As a result, overheating and explosion ofthese secondary batteries is more frequent.

SUMMARY OF THE INVENTION

The present invention is directed to a secondary battery having anadiabatic plate attached to a surface of the negative electrode plate.This adiabatic plate is attached to the surface opposite the surface towhich the negative electrode tab is fixed. This construction prevents anadditional short circuit between the negative electrode plate and thenegative electrode tab when an internal short circuit occurs. Thisconstruction also prevents an additional short circuit when theseparator melts due to heat generated from the electrode tab duringovercharging or overdischarging of the battery.

In one embodiment, the secondary battery of the present inventioncomprises an electrode assembly formed by winding a positive electrodeplate, a negative electrode plate and a separator. The positiveelectrode plate comprises a positive electrode collector, a positiveelectrode coating coated on a portion of the positive electrodecollector and at least one non-coated area on the positive electrodecollector. The negative electrode plate comprises a negative electrodecollector, a negative electrode coating coated on the negative electrodecollector and at least one non-coated area on the negative electrodecollector. The separator insulates the positive and negative electrodeplates from each other. The electrode assembly further comprisespositive and negative electrode tabs fixed to the non-coated areas ofthe positive and negative electrode plates, respectively. The negativeelectrode adiabatic plate is attached to a surface of the non-coatedarea of the negative electrode collector, and is positioned on thesurface of the collector opposite the surface on which the negativeelectrode tab is fixed.

The negative electrode adiabatic plate may comprise an organic materialselected from the group consisting of polyimide (PI), polyethyleneterephthalate (PET), and polypropylene (PP). Alternatively, the negativeelectrode adiabatic plate may comprise a composite material including anorganic material and an inorganic material. In this embodiment, theorganic material of the negative electrode adiabatic plate may comprisea material selected from the group consisting of PI, PET, and PP. Theinorganic material may comprise a material selected from the groupconsisting of oxides and nitrides. The oxides may be selected from thegroup consisting of Al₂O₃, TiO₂, ZrO₂, SiO₂, MnO₂, MgO, and mixturesthereof. The nitrides may be selected from the group consisting ofSi₃N₄, BN, and mixtures thereof.

The shape of the particles of the inorganic material of the negativeelectrode adiabatic plate is selected from the group consisting ofwhiskers, balls and plates. The diameters of the whiskers or balls, andthe thicknesses of the plates, are preferably less than 50% of thethickness of the adiabatic plate. The adiabatic plate preferably has athickness of from about 5 to about 200 μm. The inorganic materialcomprises from about 20 to about 80 wt % of the adiabatic plate.

The positive electrode plate may also have an adiabatic plate attachedto a surface of the non-coated area of the positive electrode collector.This positive electrode adiabatic plate is attached to the surface ofthe positive electrode plate opposite the surface to which the positiveelectrode tab is fixed. The positive electrode adiabatic plate may havethe same composition as the negative electrode adiabatic plate. However,the positive electrode adiabatic plate has a thickness less than that ofthe negative electrode adiabatic plate.

Insulation plates may be attached to the negative and positive electrodetabs. These insulation plates may have the same composition as thenegative electrode adiabatic plate.

The positive electrode tab may be positioned on the outer periphery ofthe electrode assembly. The negative electrode tab may be positioned onthe inner periphery of the electrode assembly. Alternatively, thepositive and negative electrode tabs may both be positioned on the innerperiphery of the electrode assembly and separated from each other by apredetermined distance.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by reference to the following detaileddescription when taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an exploded perspective view of a secondary battery accordingto the prior art;

FIG. 2 is a perspective view of an unwound electrode assembly accordingto the prior art;

FIG. 3 is a top view of an unwound electrode assembly according to oneembodiment of the present invention;

FIG. 3 a is an exploded perspective view of a secondary batteryaccording to one embodiment of the present invention;

FIG. 4 is a front view of an electrode plate of the electrode assemblyof FIG. 3;

FIG. 5 is a top view of the electrode assembly of FIG. 3 after winding;

FIG. 6 is a sectional view of an adiabatic plate according to analternative embodiment of the present invention;

FIG. 7 is a top view of a wound electrode assembly according to anotheralternative embodiment of the present invention;

FIG. 8 is a top view of a wound electrode assembly according to yetanother alternative embodiment of the present invention; and

FIG. 9 is a top view of an unwound electrode assembly according to stillanother alternative embodiment of the present invention.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will now be describedwith reference to the accompanying drawings. In the followingdescription and accompanying drawings, like reference numerals are usedto designate like components in order to omit repetitive descriptions ofsame or similar components.

FIG. 3 is a top view of an unwound electrode assembly according to oneembodiment of the present invention. FIG. 4 is a front view of anelectrode plate of the electrode assembly of FIG. 3. FIG. 5 is a topview of the electrode assembly of FIG. 3 after winding. FIG. 6 is asectional view of an adiabatic plate according to an alternativeembodiment of the present invention. FIG. 7 is a top view of an unwoundelectrode assembly according to another alternative embodiment of thepresent invention. FIG. 8 is a top view of a wound electrode assemblyaccording to yet another alternative embodiment of the presentinvention. FIG. 9 is a top view of an unwound electrode assemblyaccording to still another alternative embodiment of the presentinvention.

In one embodiment of the present invention, as shown in FIG. 3 a, alithium ion secondary battery comprises a can 110, an electrode assembly120 contained in the can 110, and a cap assembly 170 for sealing the can110. The can 110 may comprise a metallic member having the shape of acuboid, and the can itself can be a terminal. The can 110 has an opentop surface 110 a, and the electrode assembly 120 is placed in the can110 through the open top surface 110 a.

The cap assembly 170 includes a cap plate 171, an insulation plate 172,a terminal plate 173, and a negative electrode terminal 174. The capassembly 170 is coupled to a separate insulation case 170, and is thencoupled to the open top surface 110 a of the can 110, thereby sealingthe can 110.

Referring to FIGS. 3, 4 and 5, the electrode assembly 120 includes apositive electrode plate 130, a negative electrode plate 140, and aseparator 150. The separator 150 is positioned between the positive andnegative electrode plates 130 and 140, respectively, and theconstruction is then wound into a jelly roll construction.

The electrode assembly 120 has a negative electrode tab 146 positionedon its inner periphery. The negative electrode tab 146 is welded to thenegative electrode plate 140 and protrudes from the top of the electrodeassembly 120, as shown in FIG. 3 a. The electrode assembly also has apositive electrode tab 136 positioned on its outer periphery. Thepositive electrode tab 136 is welded to the positive electrode plate 130and protrudes from the top of the electrode assembly 120, as also shownin FIG. 3 a. As used herein, the “inner periphery” is the end of theelectrode assembly, which, after winding, is positioned in the center ofthe wound electrode assembly 120, as shown in FIG. 3 a. The “outerperiphery” is the end of the electrode assembly, which, after winding,is positioned on the outer edge of the wound electrode assembly, as alsoshown in FIG. 3 a.

The positive electrode plate 130 comprises a positive electrodecollector 132, a positive electrode coating 134 coated on a portion ofthe positive electrode collector 132, and a positive electrode tab 136.The positive electrode collector 132 comprises thin aluminum foil. Thepositive electrode coating 134 comprises a lithium-based oxide as itsmain component and is coated on both surfaces of the positive electrodecollector 132. The positive electrode collector 132 also comprisesnon-coated areas 132 a, which are not coated with the positive electrodecoating 134. These non-coated areas 132 a are located on both ends ofthe positive electrode collector 132.

The positive electrode tab 136 is fixed to a first surface of one of thenon-coated areas 132 a of the positive electrode collector 132 byultrasonic welding or laser welding. The positive electrode tab 136preferably comprises nickel and is positioned such that its upper endprotrudes from the upper end of the positive electrode collector 132.

The negative electrode plate 140 comprises a negative electrodecollector 142, a negative electrode coating 144 coated on a portion ofthe negative electrode collector 142, a negative electrode tab 146, anda negative electrode adiabatic plate 148. The negative electrodecollector 142 comprises thin copper foil. The negative electrode coating144 comprises a carbon material as its main component and is formed onboth surfaces of the negative electrode collector 142. The negativeelectrode collector 142 also comprises non-coated areas 142 a, which arenot coated with the negative electrode coating 144. These non-coatedareas are located on both ends of the negative electrode collector 142.

The negative electrode tab 146 preferably comprises nickel and is fixedto a first surface of one of the non-coated areas 142 a of the negativeelectrode collector 142. The negative electrode tab 146 is positioned onthe inner periphery of the electrode assembly 120 by ultrasonic welding.The negative electrode tab 146 is positioned such that its upper endprotrudes from the upper end of the negative electrode collector 142.

The negative electrode adiabatic plate 148 comprises an adhesive tapecomprising an adiabatic material having excellent heat-interruptionperformance. Nonlimiting examples of suitable adiabatic materialsinclude polyimide (PI), polyethylene terephthalate (PET), andpolypropylene (PP). The negative electrode adiabatic plate 148preferably has a thickness of from about 5 to about 200 μm. If thenegative electrode adiabatic plate 148 is too thin, i.e. if itsthickness is less than about 5 μm, its heat-interruption performancedeclines. If the negative electrode adiabatic plate is too thick, i.e.if its thickness is greater than about 200 μm, the thickness of thejelly roll construction partially increases.

The negative electrode adiabatic plate 148 is attached to a secondsurface of a non-coated area 142 a of the negative electrode collector142, and the second surface is opposite the first surface, to which thenegative electrode tab 146 is welded. The area of attachment of thenegative electrode adiabatic plate 148 is preferably larger than that ofthe negative electrode tab 146.

As shown in FIG. 5, the separator 150 is positioned between the positiveand negative electrode plates 130 and 140, respectively, insulating theelectrode plates from each other. The electrode assembly 120 is thenwound such that the positive and negative electrode tabs 136 and 146,respectively, are positioned on the outer and inner peripheries,respectively, of the wound electrode assembly 120. The negativeelectrode adiabatic plate 148 is positioned on a second surface of anon-coated area 142 a of the negative electrode collector 142, and thesecond surface is opposite the first surface, to which the negativeelectrode tab 146 is welded. This construction enables interruption ofthe heat generated by the negative electrode tab 146, thereby preventingtransmission of that heat to the separator 150 and the positiveelectrode plate 130.

In general, the sites in the electrode assembly 120 where the electrodeplates and the electrode tabs are welded together generate large amountsof heat. In particular, the site in the electrode assembly where thenegative electrode plate 140 and the negative electrode tab 146 arewelded together generates the largest amount of heat. The separatenegative electrode adiabatic plate 148 of the present invention,however, prevents the heat generated from the negative electrode tab 146from being transmitted to the separator 150 and positive electrode plate130. As a result, the separator 150 does not contract, therebypreventing a short circuit between the positive and negative electrodeplates 130 and 140, respectively.

FIG. 6 is a sectional view of an adiabatic plate according to analternative embodiment of the present invention. FIG. 6 depicts anegative electrode adiabatic plate 148 a comprising a composite materialhaving excellent heat-interruption performance, thermal resistance, andendurance. More particularly, the negative electrode adiabatic plate 148a comprises a composite material including particles of an organicmaterial 148 b having a low melting point and particles of an inorganicmaterial 148 c having a high melting point. The inorganic material 148 cmaintains the adiabatic and insulative properties of the plate 148 aeven when the temperature of the negative electrode adiabatic plate 148a increases and the organic material 148 b melts.

The negative electrode adiabatic plate 148 a comprises an adhesive tapeand preferably has a thickness of from about 5 to about 200 μm. If thenegative electrode adiabatic plate 148 a is too thin, i.e. if itsthickness is smaller than about 5 μm, the heat-interruption performancedeclines. If the negative electrode adiabatic plate 148 a is too thick,i.e. if its thickness is greater than about 200 μm, the thickness of theelectrode assembly partially increases.

The negative electrode adiabatic plate 148 a contacts the electrolyteinside the can 110 and thus must have strong resistance to theelectrolyte. Accordingly, the organic material 148 b of the negativeelectrode adiabatic plate 148 a comprises a material having excellentresistance to the electrolyte of the secondary battery. Nonlimitingexamples of suitable materials for use as the organic material 148 binclude polyimide (PI), polyethylene terephthalate (PET), andpolypropylene (PP).

The inorganic material 148 c of the negative electrode adiabatic plate148 a comprises a non-conductive material having a high melting point.Nonlimiting examples of suitable materials for use as the inorganicmaterial 148 a include oxides and nitrides. Nonlimiting examples ofsuitable oxides include Al₂O₃, TiO₂, ZrO₂, SiO₂, MnO₂, MgO and mixturesthereof. Nonlimiting examples of suitable nitrides include Si₃N₄, BN andmixtures thereof.

The particles of the inorganic material 148 c may take various shapes,including balls, whiskers, and plates. The ball-shaped or whisker-shapedparticles preferably have diameters less than about 50% of the thicknessof the negative electrode adiabatic plate 148 a. More preferably, thediameters of the ball-shaped or whisker-shaped particles are less thanabout 10% of the thickness of the negative electrode adiabatic plate 148a. Similarly, the thicknesses of the plate-shaped particles are lessthan about 50% of the thickness of the negative electrode adiabaticplate 148 a. More preferably, the thicknesses of the plate-shapedparticles are less than about 10% of the thickness of the negativeelectrode adiabatic plate 148 a. If the diameters of the ball-shaped orwhisker-shaped particles, or the thicknesses of the plate-shapedparticles of the inorganic material 148 c are larger than about 50% ofthe thickness of the negative electrode adiabatic plate 148 a, thesurface of the negative electrode adiabatic plate 148 a is not smoothand the adhesive force of the plate 148 a decreases.

In this embodiment, the weight of the inorganic material 148 c rangesfrom about 20 to about 80% of the total weight of the negative electrodeadiabatic plate 148 a. If the inorganic material 148 c comprises lessthan about 20% of the total weight of the negative electrode adiabaticplate 148 a, it becomes difficult for the inorganic material 148 c tomaintain the integrity of the negative electrode adiabatic plate 148 awhen the organic material 148 a melts. Therefore, if less than about 20wt % of the inorganic material is used, there is little advantage to useof the composite material for the negative electrode adiabatic plate 148a. If the inorganic material 148 c comprises more than about 80% of thetotal weight of the negative electrode adiabatic plate 148 a, it becomesdifficult to shape the composite material into an adhesive tape. Inaddition, the strength of the negative electrode adiabatic plate 148 adecreases. This causes problems during battery operation.

The negative electrode adiabatic plate 148 a is attached to a secondsurface of a non-coated area 142 a of the negative electrode collector142, and the second surface is opposite the first surface, to which thenegative electrode tab 146 is welded. The area of attachment of thenegative electrode adiabatic plate 148 a is preferably larger than thatof the negative electrode tab 146.

FIG. 7 is a top view showing an electrode assembly according to anotheralternative embodiment of the present invention. FIG. 7 depicts anelectrode assembly 220 comprising a positive electrode adiabatic plate238, a positive electrode tab 236 and a negative electrode tab 246.Specifically, the positive electrode adiabatic plate 238 is attached toa second surface of a non-coated area 232 a of the positive electrodecurrent collector 232, and the second surface is opposite the firstsurface, to which the positive electrode tab 236 is welded.

The positive electrode tab 236 is generally positioned on the outerperiphery of the electrode assembly 220 such that the generated heatdiffuses toward the can. When heat is rapidly generated, however, it maybe transmitted to the inner periphery of the electrode assembly 220. Thepositive electrode adiabatic plate 238 may have a thickness less thanthat of the negative electrode adiabatic plate 248 as long as thepositive electrode tab 236 is positioned on the outer periphery of theelectrode assembly 220. This construction enables the generated heat toeasily diffuse to the exterior of the electrode assembly because lessheat is generated near the negative electrode tab 246.

FIG. 8 is a top view showing an electrode assembly according to yetanother alternative embodiment of the present invention. The electrodeassembly 320 has positive and negative electrode tabs 336 and 346,respectively, both positioned on the inner periphery of the electrodeassembly 320 and spaced apart from each other by a predetermineddistance. The electrode assembly 320 further comprises a positiveelectrode adiabatic plate 338 and a negative electrode adiabatic plate348. The positive electrode adiabatic plate 338 is attached to a secondsurface of a non-coated area 132 a of the positive electrode currentcollector 332, and the second surface is opposite the first surface, towhich the positive electrode tab 338 is attached. Similarly, thenegative electrode adiabatic plate 348 is attached to a second surfaceof a non-coated area 142 a of the negative electrode current collector342, and the second surface is opposite the first surface, to which thenegative electrode tab 348 is attached. By this construction, the heatgenerated from the positive and negative electrode tabs 336 and 346,respectively, during charging or discharging of the secondary battery isnot transmitted to the separator 150 or electrode plate. Therefore, theseparator 150 neither melts nor contracts.

FIG. 9 is a top view of an unwound electrode assembly according to stillanother alternative embodiment of the present invention. As shown inFIG. 9, the electrode assembly 420 includes a positive electrodeinsulation plate 439 formed on the positive electrode tab 436, and anegative electrode insulation plate 449 formed on the negative electrodetab 446. The electrode assembly 420 further comprises a positiveelectrode adiabatic plate 438 and a negative electrode adiabatic plate448. The positive electrode adiabatic plate 438 is attached to a secondsurface of a non-coated area 432 a of the positive electrode currentcollector 432, and the second surface is opposite the first surface, towhich the positive electrode insulation plate 439 is attached.Similarly, the negative electrode adiabatic plate 448 is attached to asecond surface of a non-coated area 442 a of the negative electrodecurrent collector 442, and the second surface is opposite the firstsurface, to which the negative electrode insulation plate 449 isattached.

The positive and negative electrode tabs 436 and 446, respectively, aregenerally formed by cutting a metal plate having a predetermined shapeby press molding. This process may create a burr on one corner of eachplate. However, if the positive and negative electrode tabs 436 and 446,respectively, each comprise a burr, the burrs may extend through theseparator 450 when the electrode assembly is wound. The separator 450,which electrically insulates the positive and negative electrode plates430 and 440, respectively, may then be damaged and a short circuit mayoccur between the positive and negative electrode plates 130 and 140,respectively. Therefore, the insulation plates 439 and 449 are appliedover the positive and negative electrode tabs 436 and 446, respectively.This prevents the separator 150 from being damaged by the burrs on thepositive and negative electrode tabs 436 and 446, respectively, andprevents a short circuit from occurring between the electrode plates.

The insulation plates 139 and 149 can be applied over the positive andnegative electrode tabs 436 and 446, respectively, by attaching theinsulation plates 139 and 149 to the surface of the non-coated area 132a or 142 a to which the positive electrode tab 436 or negative electrodetab 446 is attached, as shown in FIG. 9. This construction prevents thepositive and negative electrode tabs 436 and 446, respectively, fromcontacting the separator 450 either directly or indirectly, therebypreventing any damage to the separator 450.

The insulation plates 439 and 449 can comprise the same material as theadiabatic plates 438 and 448. When the insulation plates 439 and 449comprise the same material as the adiabatic plates 438 and 448, bothadiabatic and insulative properties are obtained, thereby preventing theseparator from melting and contracting.

The present invention has been described with reference to a can-typesecondary battery having an electrode assembly with a jelly rollconstruction that is uniformly compressed. However, the presentinvention is not limited to can-type secondary batteries, but rather canbe applied to any secondary batteries using electrode assemblies havingjelly roll constructions. As such, the present invention can be appliednot only to square-type secondary batteries, but also to cylinder-typesecondary batteries, button-type secondary batteries, and primarybatteries.

The present invention prevents melting and contraction of the separatordue to heat generated from the electrode tab during overcharging oroverdischarging of the battery. In addition, the present inventionprevents melting and contracting of the separator when an internal shortcircuit occurs. By preventing the melting and contraction of theseparator, the present invention also prevents an additional shortcircuit from occurring between the electrode tabs and the electrodeplates, and particularly between the negative electrode tab and thenegative electrode plate.

Presently preferred embodiments of the present invention have beendescribed for illustrative purposes only. Those skilled in the art willappreciate that various modifications, additions and substitutions maybe made without departing from the spirit and scope of the invention asdescribed in the accompanying claims.

1. An electrode assembly for a secondary battery, the electrode assemblycomprising: a positive electrode plate comprising a positive electrodecollector and a positive electrode coating coated on a portion of thepositive electrode collector, a negative electrode plate comprising anegative electrode collector and a negative electrode coating coated ona portion of the positive electrode collector, a separator forinsulating the positive and negative electrode plates from each other, apositive electrode tab attached to the positive electrode collector, anegative electrode tab attached to the negative electrode collector, andat least one adiabatic plate attached to at least one of the negativeelectrode collector and the positive electrode collector, wherein theadiabatic plate is attached to a surface of the electrode collectoropposite the electrode tab.
 2. An electrode assembly as claimed in claim1, wherein the at least one adiabatic plate comprises a negativeelectrode adiabatic plate attached to the negative electrode collector.3. An electrode assembly as claimed in claim 2, wherein the negativeelectrode adiabatic plate comprises an organic material selected fromgroup consisting of polyimide (PI), polyethylene terephthalate (PET),and polypropylene (PP).
 4. An electrode assembly as claimed in claim 2,wherein the negative electrode adiabatic plate comprises a compositematerial comprising an organic material and an inorganic material.
 5. Anelectrode assembly as claimed in claim 4, wherein the inorganic materialof the negative electrode adiabatic plate is selected from the groupconsisting of oxides and nitrides.
 6. An electrode assembly as claimedin claim 5, wherein the inorganic material is selected from the groupconsisting of Al₂O₃, TiO₂, ZrO₂, SiO₂, MnO₂, MgO, Si₃N₄, BN and mixturesthereof.
 7. An electrode assembly as claimed in claim 4, wherein theinorganic material comprises particles having a shape selected from thegroup consisting of whiskers, balls and plates.
 8. An electrode assemblyas claimed in claim 7, wherein the particles of the inorganic materialhave thicknesses less than 50% of a thickness of the negative electrodeadiabatic plate.
 9. An electrode assembly as claimed in claim 4, whereinthe inorganic material comprises from about 20 to about 80 wt % of thenegative electrode adiabatic plate.
 10. An electrode assembly as claimedin claim 2, wherein the negative electrode adiabatic plate has athickness of from about 5 to about 200 μm.
 11. An electrode assembly asclaimed in claim 2, further comprising a positive electrode adiabaticplate attached to the positive electrode collector.
 12. An electrodeassembly as claimed in claim 11, wherein the positive electrodeadiabatic plate comprises an organic material selected from groupconsisting of polyimide (PI), polyethylene terephthalate (PET), andpolypropylene (PP).
 13. An electrode assembly as claimed in claim 11,wherein the positive electrode adiabatic plate comprises a compositematerial comprising an organic material and an inorganic material. 14.An electrode assembly as claimed in claim 13, wherein the inorganicmaterial of the negative electrode adiabatic plate is selected from thegroup consisting of oxides and nitrides.
 15. An electrode assembly asclaimed in claim 14, wherein the inorganic material is selected from thegroup consisting of Al₂O₃, TiO₂, ZrO₂, SiO₂, MnO₂, MgO, Si₃N₄, BN andmixtures thereof.
 16. An electrode assembly as claimed in claim 13,wherein the inorganic material comprises particles having a shapeselected from the group consisting of whiskers, balls and plates.
 17. Anelectrode assembly as claimed in claim 16, wherein the particles of theinorganic material have thicknesses less than 50% of a thickness of thepositive electrode adiabatic plate.
 18. An electrode assembly as claimedin claim 11, wherein the positive electrode adiabatic plate has athickness less than a thickness of the negative electrode adiabaticplate.
 19. An electrode assembly as claimed in claim 1, furthercomprising: a positive electrode insulation plate attached to thepositive electrode tab, and a negative electrode insulation plateattached to the negative electrode tab.
 20. An electrode assembly asclaimed in claim 19, wherein the positive electrode insulation plate andthe negative electrode insulation plate each comprise an organicmaterial selected from group consisting of polyimide (PI), polyethyleneterephthalate (PET), and polypropylene (PP).
 21. An electrode assemblyas claimed in claim 19, wherein the positive electrode insulation plateand the negative electrode insulation plate each comprise a compositematerial comprising an organic material and an inorganic material. 22.An electrode assembly as claimed in claim 21, wherein the inorganicmaterial is selected from the group consisting of oxides and nitrides.23. An electrode assembly as claimed in claim 22, wherein the inorganicmaterial is selected from the group consisting of Al₂O₃, TiO₂, ZrO₂,SiO₂, MnO₂, MgO, Si₃N₄, BN and mixtures thereof.
 24. An electrodeassembly as claimed in claim 21, wherein the inorganic materialcomprises particles having a shape selected from the group consisting ofwhiskers, balls and plates.
 25. An electrode assembly as claimed inclaim 24, wherein the particles of the inorganic material havethicknesses less than 50% of a thickness of the negative electrodeadiabatic plate.
 26. An electrode assembly as claimed in claim 1,wherein the positive electrode tab is positioned on an outer peripheryof the electrode assembly, and the negative electrode tab is positionedon an inner periphery of the electrode assembly.
 27. An electrodeassembly as claimed in claim 1, wherein the positive electrode tab andthe negative electrode tab are both positioned on an inner periphery ofthe electrode assembly.
 28. An electrode assembly as claimed in claim 1,wherein the positive and negative electrode tabs each comprise nickel,the negative electrode collector comprises copper foil and the positiveelectrode collector comprises aluminum foil.
 29. An electrode assemblyas claimed in claim 1, wherein an area of attachment of the negativeelectrode adiabatic plate is greater than an area of attachment of thenegative electrode tab.
 30. An electrode assembly for a secondarybattery, the electrode assembly comprising: a positive electrode platecomprising a positive electrode collector and a positive electrodecoating coated on a portion of the positive electrode collector, anegative electrode plate comprising a negative electrode collector and anegative electrode coating coated on a portion of the positive electrodecollector, a separator for insulating the positive and negativeelectrode plates from each other, a positive electrode tab attached tothe positive electrode collector, a negative electrode tab attached tothe negative electrode collector, and a negative electrode adiabaticplate attached to the negative electrode collector, wherein the negativeelectrode adiabatic plate is attached to a surface of the negativeelectrode collector opposite the negative electrode tab, and a positiveelectrode adiabatic plate attached to the positive electrode collector,wherein the positive electrode adiabatic plate is attached to a surfaceof the positive electrode collector opposite the negative electrode tab.31. An electrode assembly as claimed in claim 30, further comprising: apositive electrode insulation plate attached to the positive electrodetab, and a negative electrode insulation plate attached to the positiveelectrode tab.
 32. An electrode assembly as claimed in claim 30, whereinthe negative electrode adiabatic plate has a thickness ranging fromabout 5 to about 200 μm, and the positive electrode adiabatic plate hasa thickness less than the thickness of the negative electrode adiabaticplate.
 33. An electrode assembly as claimed in claim 30, wherein thepositive and negative adiabatic plates each comprise an organic materialselected from group consisting of polyimide (PI), polyethyleneterephthalate (PET), and polypropylene (PP).
 34. An electrode assemblyas claimed in claim 30, wherein the positive and negative electrodeadiabatic plates each comprise a composite material comprising anorganic material and an inorganic material.
 35. An electrode assembly asclaimed in claim 32, wherein the inorganic material is selected from thegroup consisting of Al₂O₃, TiO₂, ZrO₂, SiO₂, MnO₂, MgO, Si₃N₄, BN andmixtures thereof.
 36. An electrode assembly as claimed in claim 30,wherein the positive electrode tab is positioned on an outer peripheryof the electrode assembly, and the negative electrode tab is positionedon an inner periphery of the electrode assembly.
 37. An electrodeassembly as claimed in claim 30, wherein the positive electrode tab andthe negative electrode tab are both positioned on an inner periphery ofthe electrode assembly.